A DoF-Optimal Scheme for the two-user X-channel with Synergistic Alternating CSIT

TL;DR

This paper introduces a novel scheme for the two-user X-channel that leverages alternating CSIT to achieve optimal degrees of freedom, demonstrating significant gains over traditional methods.

Contribution

It proposes a new interference management scheme utilizing interference creation-resurrection with alternating CSIT to reach the DoF upper bound.

Findings

Achieves 4/3 DoF for certain CSIT patterns

Identifies patterns with synergistic and dissociative effects

Demonstrates the potency of interference creation-resurrection technique

Abstract

In this paper, the degrees of freedom (DoF) of the two-user single input single output (SISO) X-channel are investigated. Three cases are considered for the availability of channel state information at the transmitters (CSIT); perfect, delayed, and no-CSIT. A new achievable scheme is proposed to elucidate the potency of interference creation-resurrection (IRC) when the available CSIT alternates between these three cases. For some patterns of alternating CSIT, the proposed scheme achieves $4/3$ DoF, and hence, coincides with the information theoretic upper bound on the DoF of the two-user X-channel with perfect and instantaneous CSIT. The CSIT alternation patterns are investigated where the patterns that provide extraordinary synergistic gain and dissociative ones are identified.